LiNiFe-based layered structure oxide and composite for advanced single layer fuel cells

• Single layer fuel cell (SLFC) based on layer structured oxide Fe doped LiNiO2 (LNF).
• Electrical properties and electrode catalytic activity are investigated.
• Balanced ionic and electronic conductivity of LNF-SDC composite.
• Super-performance of SLFC based on LNF-SDC composite.
• 2.76 times improvement of power output of LNF-SDC based SLFC over LNF based SLFC.

A layered structure metal oxide, LiNi0.1Fe0.90O2−δ (LNF), is explored for the advanced single layer fuel cells (SLFCs). The temperature dependent impedance profiles and concentration cells (hydrogen concentration, oxygen concentration, and H2/air atmospheres) tests prove LNF to be an intrinsically electronic conductor in air while mixed electronic and proton conductor in H2/air environment. SLFCs constructed by pure LNF materials show significant short circuiting reflected by a low device OCV and power output (175 mW cm−2 at 500 °C) due to high intrinsic electronic conduction. The power output is improved up to 640 and 760 mW cm−2, respectively at 500 and 550 °C by compositing LNF with ion conducting material, e.g., samarium doped ceria (SDC), to balance the electronic and ionic conductivity; both reached at 0.1 S cm−1 level. Such an SLFC gives super-performance and simplicity over the conventional 3-layer (anode, electrolyte and cathode) FCs, suggesting strong scientific and commercial impacts.